1. Field of the Invention
The present invention generally relates to a motor driven mortar applying device for laying two beads of mortar along the top surface of a wall under construction.
2. Description of the Prior Art
Brick and block walls are assembled by skilled masons by applying mortar to the top and side surfaces of the bricks or blocks and stacking them in a stable configuration. Automating some of the operations performed by the mason would result in considerable savings in labor charges. For many years, efforts have been made to partially automate the procedure of applying mortar to the top surfaces of a wall of bricks or blocks. For example, U.S. Pat. No. 2,341,691 to Ciceske, U.S. Pat. No. 2,591,377 to Sadler, U.S. Pat. No. 3,545,159 to Brewer, U.S. Pat. 3,826,410 to Meyer, U.S. Pat. No. 4,135,651 to Hession et al., and U.S. Pat. No. 4,352,445 to Cusumano et al. each show mortar applying devices that are pushed or pulled across the top surface of a wall. In addition, U.S. Pat. No. 2,683,981 to Richey, U.S. Pat. No. 3,791,559 to Foye, and U.S. Pat. No. 3,887,114 to Villanovich each show wheeled mortar applying devices that are propelled across the top of a wall under construction by an operator turning a hand crank that drives the wheels. Most of the above-identified patents show the deposition of two beads of mortar along the top outer edges of the blocks in the wall.
A severe limitation of all the mortar applying devices shown in the above-identified patents is the requirement that an operator be present to move the mortar applying device across the top surface of the wall under construction. A hand propelled or maneuvered mortar applying device necessarily ties up one of the masons at a job site, thereby lowering the total productivity of the group. In addition, because an operator must stand and move alongside the wall under construction, he is in constant danger of bumping and moving the mason's line which is used for aligning the blocks that are being laid. Hence, a power driven mortar applying device represents a marketable improvement in terms of both the productivity of each of the masons at the job site and in maintaining the integrity of the mason's line. U.S. Pat. No. 4,043,487 to Price shows an example of a mortar applying device which is power driven. However, the Price design does not allow easy unsupervised application of mortar on top of the wall since it does not have an automatic cut off feature for sensing when the wall ends.
Many mortar applying devices use internal elements which contact the mortar while it is being deposited. For example, U.S. Pat. No. 3,162,886 to Wise discloses a mortar applying device which includes an auger for driving the mortar toward the exit ports, U.S. Pat. No. 2,683,981 to Richey discloses the use of impellers to stir the mortar, U.S. Pat. No. 3,791,559 shows the use of mortar working blades, and U.S. Pat. No. 4,352,445 to Cusumano et al. shows the use of paddles to even out the mortar in the beads which have been laid. Elements which contact the mortar present serious clean up problems for masons. If mortar is allowed to harden on the moving element, as would happen if the mortar applying device was not thoroughly washed at the end of a day, the mason is forced to chisel the element free before the device can be used again.
U.S. Pat. No. 4,135,651 to Hession et al. and U.S. Pat. No. 3,545,159 to Brewer show the use of gravitational forces in dispensing the mortar on the blocks in a wall, and U.S. Pat. No. 3,826,410 to Meyer and U.S. Pat. No. 4,043,487 to Price show the use of gravitational forces assisted by vibration. If gravity is to be used as the mortar feed mechanism, care must be taken to assure that the mortar is dispensed at approximately the same rate irrespective of the amount of mortar present in the hopper. Some prior mortar applying devices which use gravity suffer from the fact that mortar will be dispensed faster at the beginning of a run when the hopper is full, because of the downward force exerted by the weight of the mortar in the hopper, than at the end of the run when the hopper is nearly empty. Such a situation will lead to an uneven thickness of mortar in the wall which is unacceptable for proper construction.